The occurrence of renal dysfunction following administration of intravenous contrast media is fairly common. When defined as a rise in serum creatinine with or without oliguria, the magnitude and severity of contrast associated nephropathy (CAN) varies from an asymptomatic rise in serum creatinine to oliguric renal failure requiring dialysis. In the setting of pre-existing disease and certain other risk factors, CAN characterized by severe oliguric renal failure requiring dialysis may supervene within 1 to 5 days of the angiographic procedure, with an incidence as high as 20%. We propose that mannitol would be protective against CAN in patients with pre-existing renal disease undergoing angiography. Only those patients not hospitalized are seen on the GCRC on an outpatient basis for the followup assessments. A total of 30 patients have been studied to date. Of these, four patients have progressed to oliguric renal failure requiring dialysis. No significant results have been accrued to date.